Technical Field
The disclosure relates in general to a display apparatus and more particularly to a display apparatus having a diffractive optical element.
Description of the Related Art
Currently, an image display device mainly comprises a liquid crystal display device, a plasma display device, an OLED display device and an electronic paper display device, etc. The liquid crystal display device is a non-self-luminous display device, and thus usually needs a backlight source for generating light that entering the liquid crystal display panel with a uniform plane profile through an optical film such as a diffusion film, a brightness enhancement film, etc, for displaying an image.
A conventional wide viewing angle liquid crystal display device such as a vertical aligned or multi-domain vertical aligned liquid crystal display device has a wide viewing angle. However, an image displayed by it at some specific observation angles needs to be improved. For example, there is an obvious difference of the image color and brightness at different observation angles of the left, right side and the front view. In addition, the difference of the image color and brightness would increase as the viewing angle increases. At some special viewing angles of the upper left side, the lower left side, the upper right side, the lower left side, and the image deviation problem is more serious. In addition, the contrast-decreasing problem also occurs due to light leakage.
Therefore, a display apparatus for improving image quality problems such as difference of image color, brightness, etc is need.